1. Field of the Invention
This invention pertains generally to the field of acoustic wave systems and devices, and more particular to systems used to affect the behavior of animals. In a more particular embodiment of the invention, predator sound waves are combined with other sounds to yield music which is accepted or pleasurable to mankind, and which simultaneously is useful to affect the behavior of specific animals. In an even more particular embodiment, the invention pertains to the field of mosquito or other airborne pest control, and integrates dragonfly sounds into music to repel mosquitoes while providing pleasurable entertainment to humans.
2. Description of the Related Art
For time immemorial, man has sought ways to adapt his environment in ways which are generally perceived as beneficial. The desire for making changes to one's environment are generally based upon important issues such as health and well-being.
Louis Pasteur, who is often cited as the father of modern disease theory, identified and publicized cause and effect relationship between microbiological agents and disease. This forever influenced the understanding of disease, and has continued to lead to an ever greater understanding of the vectors of disease transmission. However, understanding disease transmission is only one component of disease prevention and human health. Another necessary component is the disruption of the usual transmission vector, whereby the disease is not allowed to pass through a normal cycle.
The economic impact of unchecked disease vectors should not be underestimated. For example, while mosquitoes are perceived by many persons only as annoying pests that may induce short-term skin irritation, their affect on mankind is far more consequential. Historically in the Untied States, mosquito-borne disease presented a serious problem for early western settlers. In the late 1800's two crews were hired for each logging camp, because it was not unusual for half of the workers to be out at any one time with malaria. This mosquito-transmitted blood parasite continued to be a problem in many parts of the U.S. into the early 1950's, when it was brought under control by eliminating human sources of infection. Humans infected with the parasite are the only source of malaria infection, and with the appearance of effective drugs, window screens and a better understanding of mosquitoes and the disease, human malaria in the U.S. was eliminated. Malaria is not the only mosquito-borne disease that has caused problems in the past. In the early 1940's hundreds of cases of equine encephalitis were reported in the mid-west and west each year. It wasn't until the 1950's however that the first human cases of mosquito-borne encephalitis were recognized. Even today, human and equine cases of encephalitis are not rare occurrences.
Using the mosquito as a continuing example, this pest is a known vector for the transmission of Eastern equine encephalitis, Japanese encephalitis, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, Western equine encephalitis, Rift Valley Fever, Yellow Fever, Dengue Fever, Dog heartworm, and malaria, among other diseases. In 1997, dengue was considered by some to be the most important mosquito-borne viral disease affecting humans; its global distribution is comparable to that of malaria. An estimated 2.5 billion people live in areas at risk for epidemic transmission. Each year, tens of millions of cases of dengue fever occur and, depending on the year, up to hundreds of thousands of cases of DHF. The case-fatality rate of DHF in most countries is about 5%. Most fatal cases are among children and young adults. Dengue is primarily a disease of the tropics, and the viruses that cause it are maintained in a cycle that involves humans and Aedes aegypti, a domestic, day-biting mosquito that prefers to feed on humans. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. The emergence of dengue/DHF as a major public health problem has been most dramatic in the American region. In an effort to prevent urban yellow fever, which is also transmitted by Ae. aegypti, the Pan American Health Organization organized a campaign that eradicated Ae. aegypti from most Central and South American countries in the 1950s and 1960s. As a result, epidemic dengue occurred only sporadically in some Caribbean islands during this period. The Ae. aegypti eradication program, which was officially discontinued in the United States in 1970, gradually eroded elsewhere, and this species began to reinfest countries from which it had been eradicated. In 1997, the geographic distribution of Ae. aegypti is wider than its distribution before the eradication program.
With the development of modern industry, many new and generally useful nuclear, biological and chemical compounds have been discovered or created that are known to have certain desirable characteristics, including the interruption of disease transmission vectors. Unfortunately, the history of these compounds has been checkered by unexpected side effects that are all too often disruptive in ways that ultimately lead to a completely new and unexpected problem. Examples are the early identified effectiveness of the chemical compound dichlorodiphenyltrichloroethane, commonly known as DDT, in the eradication of lice and mosquitoes.
Between the realization of the pesticidal activity of DDT during World War II and the present, competition between man and his competitors has been substantially achieved through chemical warfare. One textbook from the mid-1970's referred to these chemicals as “a complex arsenal of synthetic compounds of carbon, hydrogen, oxygen, and at least one other element such as chlorine, arsenic, mercury, sulfur, or phosphorus.” Unfortunately, and as already noted, this arsenal of weapons has, over time, been determined to have adverse impact on mankind and the environment that must be considered in weighting the benefits of the compounds with the associated risks.
The Agency for Toxic Substances and Disease Registry (ATSDR), as an agency of the U.S. Department of Health and Human Services, was created to serve the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and disease related to toxic substances. The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 104 (i), as amended by the Superfund Amendments and Reauthorization Act (SARA), requires ATSDR and the EPA to prepare a list, in order of priority, of substances that are most commonly found at facilities on the National Priorities List (NPL) and which are determined to pose the most significant potential threat to human health due to their known or suspected toxicity and potential for human exposure at these NPL sites. CERCLA also requires this list to be revised periodically to reflect additional information on hazardous substances. ATSDR ranks Lindane 33 of 275 on the 2001 CERCLA Priority List of Hazardous Substances. DDT is 12, Chlordane 19. The list is replete with these elements that were, and, in some cases, continue to be used as a part of the “chemical arsenal” which disrupts the disease vectors. Unfortunately, many of these chemical compounds are persistent, meaning they either do not degrade or do so very slowly.
Total eradication of mosquitoes responsible for bearing disease does not appear to be plausible with chemical warfare, at least not without even greater risk to mankind and the environment than the risks from the mosquito. Yet, in view of the serious health threat that these mosquito-borne diseases present to the human population, alternative ways to control the environment which do not have the recognized or potential toxicity of the chemical compounds of the past are needed. According to one visionary, “the future will depend on our wisdom not to replace one poison with another.”
Nevertheless, no highly effective technique that is considered to be generally acceptable for breaking the disease vector path of the mosquito has been proposed other than the chemical arsenal described herein above. For example, at a recent national conference on techniques for avoiding the transmission of mosquito-borne illness, only rudimentary techniques were proposed that may be used to reduce one's risk for becoming infected. These techniques, which are beneficial but not total solutions, included repairing window screens, removing heavy brush and trees, emptying small containers, regularly changing the water in vases, pot plants, bird baths, pets' containers and any other receptacles which hold water, keeping swimming pools chlorinated or salted, or emptying them completely when not in use for long periods, emptying children's wading pools regularly, and opening clogged drainage ditches. Other listed techniques for reducing risk include avoiding exposure at dusk and dawn, when mosquitoes are more active; wearing long, loose clothing; using a repellent such as N,N-Diethyl-M-Tolumide (DEET) Compound; using sprays, coils and vaporising devices to kill mosquitoes; using mosquito netting including possibly treating the nets with a repellent/insecticide; flushing unused toilets once a week; keeping drains and roof guttering in good repair and free of leaves and debris; keeping fish ponds stocked with fish; ensuring that tanks have close-fitting tops, lids, covers and inlet pipes to exclude mosquitoes, and screening all water inlets and the outlet end of overflow pipes. What is desired then is a way to assist with the control of the environment while not introducing further risks that may, as yet, be unknown to those within the controlled environment.
Acoustic waves have been used in the prior art to control an environment without consequential and long-term alteration. The fundamental precept of this technique is that there are certain sounds that are irritating to one or more species within the animal kingdom, and that these certain sounds may be used to selectively drive those species from an area. While the precept is correct, several factors have prevented widespread effective use of acoustic systems. One factor is a general lack of sounds that are selective to only one or a few species. In other words, and for exemplary purposes only, ultrasonic repellants have been designed which are intended to repel various rodents and flying insects. The ultrasonic adjective is used to identify that the sound waves are of higher frequency than normally detected by the human ear. Exemplary of these concepts are U.S. Pat. Nos. 5,341,762 to Petersen, which is designed for pest control, and 5,418,518 to Schenken et al, which is designed to provide a warning signal to deer and the like of an oncoming vehicle. Other species are responsive to sonic waves, such as shown in 3,317,889 to Barrand, which discloses vibrational waves in water of between 100 and 14,000 Hertz to drive sharks from an area. Each of these patents are designed to use sound waves to control an environment for the benefit of people.
Unfortunately, ultrasonic sounds may irritate or even deafen certain desired animals that are also sensitive to sounds in the same acoustic spectrum as used to deter a pest. It is well-known, for example, to use an ultrasonic horn as a deterrent during dog training, owing to a dog's elevated sensitivity to sounds within the ultrasonic spectrum. Furthermore, many rodents which are common house pets are also sensitive to ultrasound. Consequently, the overlap of detectable spectrum among desired and undesired animals has presented an obstacle in the prior art to successful use of acoustic control. This is especially true of the Petersen technology, where the desired sound pressure levels are extremely high.
Compounding the problems that limit ultrasonic pest control is an awareness that certain pests will become immune, or deaf, to continuous high volume ultrasonic sounds. Inventions such as the Quittner horn of U.S. Pat. No. 3,138,138 seek to overcome this limitation by providing intermittent activation of the acoustic wave. Nevertheless, the volumes required are difficult to produce and maintain in an area sufficient to adequately deter pests, and the probability of the pest becoming “immune” to the sound is relatively great.
Where the desired animal behavioral control spectrum overlaps that of human hearing, the sounds of the controlling device are known to be annoying and irritating to people as well as pest, and so are unacceptable for most purposes. Examples of this type of system are U.S. Pat. Nos. 5,977,866 to Joseph, Jr. et al, 5,864,516 to Brown et al, and 5,515,026 to Ewert. In the Joseph patent, chaotic noises are used to discourage birds from entering the area of an airfield. While the system may perform well for the airfield, where few persons will be found and where most persons will be wearing ear protectors, in ordinary locations occupied by persons this system would prove irritating and unacceptable. Two additional patents, U.S. Pat. No. 5,349,774 to Parra and U.S. Pat. No. 6,285,630 to Jan, illustrate the use of predator sounds to discourage a species which is prey to the predator from entering the area. Unfortunately, the sound of a predator such as a shark or hawk is not associated with enjoyment by most persons, nor would continuous exposure to repeated predator sounds be anticipated to be well received by most persons.